Adefovir-induced Fanconi syndrome associated with osteomalacia

• Main Authors: Samel Park, Woo-Il Kim, Dai-Hyun Cho, Yeo-Joo Kim, Hong-Soo Kim, Ji-Hee Kim, Seung-Kuy Cha, Kyu-Sang Park, Ji-Hye Lee, Sang Mi Lee, Eun Young Lee
• Format: Article
• Language: English
• Published: Korean Association for the Study of the Liver 2018-09-01
• Series: Clinical and Molecular Hepatology
• Subjects: Adefovir; Fanconi syndrome; Mitochondria; Proximal tubules; Osteomalacia
• Online Access: http://e-cmh.org/upload/pdf/cmh-2017-0009.pdf
• ISSN: 2287-2728; 2287-285X

Fanconi syndrome is a dysfunction of the proximal renal tubules that results in impaired reabsorption and increased urinary loss of phosphate and other solutes. The pathophysiology of drug-induced Fanconi syndrome is unclear. Here we report the case of a 36-year-old woman who presented with pain in multiple bones and proteinuria. She had a 7-year history of taking adefovir at 10 mg/day for chronic hepatitis B. Three years previously she had received surgery for a nontraumatic right femur neck fracture, after which she continued to complain of pain in multiple bones, and proteinuria, glycosuria, and phosphaturia were noted. The findings of a light-microscope examination of a renal biopsy sample were normal, but mitochondrial damage of the proximal tubules was evident in electron microscopy. Western blot analysis revealed that the level of serum fibroblast growth factor 23 (FGF23) was lower than in normal controls. After 2 months of treatment, hypophosphatemia and proximal tubular dysfunction were reversed, and serum FGF23 had normalized. This case suggests that direct mitochondrial damage in proximal tubules can cause drug-induced Fanconi syndrome associated with osteomalacia.